code: def _not_ignore(rule):
      return (True, rule[1:]) if rule.startswith("!") else (False, rule)
  
file_path: dvc/dvc/pathspec_math.py
imports: from collections import namedtuple
  from pathspec.util import normalize_file
  from dvc.utils import relpath
label_desc: Use image node_id 1 for calling a global function with example usage: _not_ignore(rule) and returns: unknown